Autism in tuberous sclerosis complex is related to both cortical and subcortical dysfunction

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Abstract
Objective: To examine the relationship between autism and epilepsy in relation to structural and functional brain abnormalities in children with tuberous sclerosis complex (TSC). Methods: Children with TSC and intractable epilepsy underwent MRI as well as PET scans with 2-deoxy-2-[18F]fluoro-d-glucose (FDG) and α-[11C]methyl-l-tryptophan (AMT). Based on the results of Autism Diagnostic Interview–Revised, Gilliam Autism Rating Scale, and overall adaptive behavioral composite (OABC) from Vineland Adaptive Behavior Scale, subjects were divided into three groups: autistic (OABC < 70; n = 9), mentally-retarded nonautistic (OABC < 70; n = 9), and relatively normal intelligence (OABC ≥ 70; n = 8). Results: PET studies showed that the autistic group had decreased glucose metabolism in the lateral temporal gyri bilaterally, increased glucose metabolism in the deep cerebellar nuclei bilaterally, and increased AMT uptake in the caudate nuclei bilaterally, compared to the mentally-retarded nonautistic group. In addition, a history of infantile spasms and glucose hypometabolism in the lateral temporal gyri were both significantly associated with communication disturbance. Glucose hypermetabolism in the deep cerebellar nuclei and increased AMT uptake in the caudate nuclei were both related to stereotypical behaviors and impaired social interaction, as well as communication disturbance. Conclusions: These results suggest that generalized epilepsy in early life and functional deficits in the temporal neocortices may be associated with communication delays, and that functional imbalance in subcortical circuits may be associated with stereotypical behaviors and impaired social interaction in children with TSC.